One of the 12 addresses raided in Sydney was a post office in the residential suburb of Sylvania Waters, south of the city.

Three men were arrested, including a 30-year-old post office owner. He and two other men in their 20s have been charged with a number of offenses including supplying firearms and fraud. A 28-year-old woman was also arrested and is helping police with their inquiries, they said.

"The syndicate had worked together to place orders in Germany for firearms to be imported into Australia. They had produced what we'll allege to be fraudulent documents allowing those firearms to be imported into Australia," Acting Assistant NSW Police Commissioner Mal Lanyon told a press conference Wednesday.

It is believed that the syndicate imported between 160 and 220 guns into the country between late 2011 and February of this year. Investigations are underway to track down the dozens of weapons that are still missing.

"We will be alleging these guns were being imported specifically for use by criminals, including outlaw motorcycle gang members and those in Middle Eastern organized crime groups. One firearm has been linked to a south-western Sydney shooting and we are making further inquiries to see if others are similarly linked," NSW Police Commissioner Andrew Scipione said in a statement.

"As evidenced by the recent shootings on our streets, illegal firearms are a blight on our society. There is no doubt in my mind that we have prevented a significant number of illegal handguns making their way into Sydney," he added.

There have been an alarming number of drive-by shootings in Sydney in recent months, many believed to be tit-for-tat exchanges between local crime gangs. The most recent was Tuesday, when shots were fired into the front window of a home in the southern suburb of Bexley. A family of four was inside, including two children aged nine and 10. None were injured.

In January, a spate of shootings, including the near-miss of a two-month-old baby sleeping in her cot, prompted the launch of Operation Spartan, a police campaign to crack down on organized gun crime and gangs.

Extra officers were deployed in criminal hotspots to conduct random searches of people and cars. To date, 187 people have been arrested and charged with more than 300 crimes. Twenty-six guns have been seized.

According to the NSW Bureau of Crime Statistics and Research, an average of 6.75 drive-by crimes were recorded each month in the year to June 2011.

Police said a direct link could be made between the number of shootings and the illegal importation of handguns.

"I think there's irrefutable evidence that a number of firearms that have been used by organized crime groups and individuals engaged in organized crime are imported," Lanyon said.

"Hand guns are not manufactured in Australia and it's very clear that hand guns are the preferred choice for organized crime because of their conceal-ability and because of their transportability, the ability to be passed around," he added.

Police said Tuesday's raid was the result of investigations which traced a number of illegal firearms back to the same batch manufactured in a Glock factory in Austria in November 2011.

The Austrian-made guns were allegedly sold through a number of companies to a German firearms dealership. The guns were then shipped from Germany to Australia using fraudulent documents.

Police in Australia worked closely with the German Federal Police in recent weeks to investigate the racket, NSW police said. So far no arrests have been made in Germany.